Benzothiazole azo isonicotinic acid compounds



United States Patent BENZOTHIAZOLE AZO ISONI COTINIC ACID COMPOUNDSJames M. Straley and Ralph R. Giles, Kingsport,

asignors to Eastman Kodak Company, N. Y., a corporation of New Jersey NoDrawing. I Application November 4, 1954 Serial No. 466,955

17 Claims. (Cl. 260-146) Teun., Rochester,

This invention relates to new azo compounds and their ..application tothe art of dyeing or coloring. More particularly it relates to certainmetallized and non-metallized benzothiazole azo isonicotinic acidcompounds and their application to the dyeing or coloration of variousmaterials. Insofar as dyeing or coloration is concerned, the inventionis particularly directed to the dyeing or coloration of celluloseacetate textile materials with the metallized azo compounds of theinvention.

The non-metallized monoazo compounds of our invention have theformula:

ing the formula I in complex combination with chromium,

cobalt, copper, iron, manganese, nickel or vanadium. The manner ofpreparing the non-metallized and metallized azo compounds of ourinvention is fully described hereinafter.

While our invention relates broadly to the non-metallized and themetallized monoazo compounds just described, the azo compounds of ourinvention are represented for the most part by the non-metallized andthe metallized forms of the azo compounds having the formula:

(I C 0 OR wherein Ar represents an ortho-arylene radical of the benzeneseries and R represents an alkyl group having 1 to 4 carbon atoms.

As is well known, one of the disadvantages dyed cellulose acetatetextile fabrics suffer in comparison with (III) 7 i 8.

some of the dyedcompeting textile fabrics, such as cot ton, wool andviscose, for example, is lack of fastness to washing. Many schemes havebeen proposed to remedy this situation but all suffer from somesignificant fault. By means of our invention dyed cellulose acetatetextile materials having good to excellent fastness to washing, lightand gas are obtainable. These results may be obtained by dyeing thecellulose acetate textile material with the non-metallized dye compoundsof the invention and then treating the dyed cellulose acetate textilematerial with suitable metal salts which cause the original dye to formmetallic complexes which are resistant, for example, to the action ofwashing, light and gas. Thus, by means of the present invention, thedisadvantage noted above with respect to the wash fastness of dyedcellulose acetate textile materials is either entirely or largelyovercome.

While reference has been made to the dyeing of cellulose acetate textilematerials, itis to be understood that the invention is generallyapplicable to the dyeing of textile materials made of or containing acellulose alkyl carboxylic acid ester having two to four carbon atoms inthe acid groups thereof. By cellulose alkyl carboxylic acid estershaving two to four carbon atoms in the acid groups thereof, we mean toinclude, for example, both hydrolyzed and unhydrolyzed celluloseacetate, cellulose propionate, cellulose butyrate, celluloseacetate-propionate and cellulose acetate-butyrate. Cellulose acetate hasbeen particularly referred to because it is the most widely usedcellulose alkyl carboxylic acid ester.

The non-metallized monoazo compounds of our invention are prepared bydiazotizing a Z-aminobenzothiazole compound having the formula:

C-NH:

wherein Ar represents an ortho-arylene radical of the benzene series andcoupling the diazonium compound obtained with an isonicotinic acidcompound having the formula:

( COOR no ox N wherein R and X have the meaning previously assigned tothem.

The metallized monoazo compounds of our invention are prepared bytreating the non-metallized azo compounds having the formula I withsalts of nickel, cobalt, copper, chromium, manganese, iron or vanadium.The non-metallized monoazo compounds can be metallized either on or offthe fiber. Metallization can be carried out, for example, by treatingthe non-metallized dye with a solution or dispersion of the metallizingagent. Although the metal complex is often formed at room temperature,we prefer to accelerate the process by heating,

usually with steam, for a short-time. The preparation of the metallizedmonoazo compounds of our invention is fully described hereinafter.

Illustrative of the metallizing agents that can be employed are thehalides, the sulfates, the acetates, the cyanides, and the thiocyanatesof nickel, cobalt, chromium, manganese, iron and vanadium as well asvarious copper compounds. Thus, nickel chloride, nickel bromide, nickelsulfate, nickel acetate, nickel cyanide, nickel formate, nickelthiocyanate .[Ni(SCN) cobaltous bromide, cobaltic chloride, cobaltouschloride, cobaltous acetate, cobaltous cyanide, cobalt thiocyanatecupric chloride, cupric bromidecupric-acetate, cupric lactate, chromiumtrichl o ride, chromium tribromide, chromic Sulfate r m sass ate chr miuthiocyanate C .3L ma an s shl x tle a anou sulfate, manganese acetate,manganese thi qcyanate [Mn($CN) ferric chloride, ferric fluoride,ferrous .a c ctate, ferrous thiocyanate [Fe(SCN) ferric thiocyanate['Fe(SCN) and vanadium thiocyanate, are illustratiye of the metallizingagents that canbe employed.

When the metal complex is formed on a cellulose alkyl carboxylic acidester, such as cellulose acetate, fiber the use of a metal thiocyanateappears to be advantageous and is preferred. Nickel thiocyanate appearsto be especially useful and particular claim is laid to its use. Next tonickel thiocyanate the use ofcobalt thiocyanate is preferred.

2 amino 6 methylsulfonylbenzothiazole, 2 amino- 6 ethylsulfonylbenzothiazole, 2 arnino v6 n propylsulfonylbenzothiazole, 2amino 6 n butylsul' fonylbenzothiazole, 2 aminobenzothiazole 6 Nmethylsulfonamide, 2 aminobenzothiazole 6 N ethylsulfonamide, 2aminobenz othiagole 6 N npropylsulfonamide, 2 aminobenzothiazole 6 Nnbutylsulfonamide, 2 amino 6 -.rnethoxybenzothiazole, 2 amino 6ethoxybenzothiazole, 2 amino -.6 n propoxybenzothiazole, 2 1' amino 6 nbutoxybenzothiazole, 2 amino 6 methylbenzothiazole, 2 amino- 6 ethylbenzothiazole, 2 amino 6 npropylbenzothiazole, 2 amino- 6 nbutylbenzothiazgile, 2- amino- 6 p hydroxyethylbenzothiazole, 2 amino 6'y hydroxypropylbenzothiazole, 2 amino 6 3 hydroXybutylbenzothiazole, 2amino -.6 acetylaminobenzothiazole, 2 amino 6 npropionylaminobenzothiazole, 2 amino 6 n butyrylaminobenzothiazole, 2amino- 6 thiomethylbenzothiazole, 2 4 amino 6 thiocyanobenzothiazole, 2amino 6 cyanobenzothiazole, 2- amino 6 trifluoromethylbenzothiazole, -2amino ,6- chlorobenzothiazole, 2 amino ,6 nitrobenzothiazole, 2 amino 4i sth ybsn gth a qle 2 amin 5,6 dimethoxybenzothiazole, 2 amino 4,7diethoxybenzothiazole, and 2 amino 4,6 dimethylbenzothiazole arerepresentative of the 2-aminobenzothiazole compounds used in thepreparation of the azo compounds of our invention.

Citrazinic acid (2,G-dihydroxyisonicotinic acid), methyl citrazinate(methyl 2,6-dihydroxyisonicotinate), ethyl citrazinate, n-propylcitrazinate, "isopropyl citrazinate, n-butyl citrazinate, isobutylcitrazinate, secondary butyl citrazinate, cyclohexyl citrazinate,fi-rnethoxycthyl citrazinate, B-ethoxyethyl citrazinate,B-n-propoxyethyl citpaz i fih l tezit tetm th w2-113 .drwmethoxyisonicotinate, ethyl 2-hydroxy-6-ethoxyisonicotinate, ethyl2-hYdIQXY-6IlPIOPOXYiSQIliQOtiHfltB, ethyl 2- y y- -b y on wt ate s prpy i2-hyd xymethoxy-isonicotinate, n-butyl 2-hydroxy 6 nbutoxyisonicotinate, isobutyl 2-hydroxy-6-ethoxyisonicotinate, secondarybutyl 2-hydroxy-6-methoxyisonicotinate, cyclohexyl2-hydroxy-6-methoxyisonicotinate, cyclohexyl 2-hydroxy-6-ethoxyisonicotinate, cyclohexyl 2-hydroxy-6- nbutoxyisonicotinate, 2 hydroxy 6 methoxyiso iCQ tinic acid,2-hydroxy-6-ethoxyisonicotinic acid, Z-hydroxy- 6-n-propoxyisonicotinicacid and 2-hydroxy-6-n-butoxyisonicotinic acid, for example, areillustrative of the isonicotinic acid compounds used in the preparationof the azo compounds of our invention.

The non-metallized monoazo dye compounds of our invention have varyingutility for the dyeing of cellulose alkyl carboxylic acid esters havingtwo to four carbon atoms in the acid groups thereof, nylon,acrylonitrile polymers, such as polyacrylonitrile and acrylonitrilegraft polymers, and polyesters, such as polyethylene terephthalate.After application to these materials, usually in the form of textilematerials, the dye may be metallized thereon, if desired. The metallizedazo compounds of our invention can be applied by ordinary dyeing orprinting techniques to nitrogenous textile materials such as wool, silk,nylon: and acrylonitrile polymers, for example. Coloration can also beeffected by incorporating the nonmetallized or metallized azo-compoundsinto the spinning dope, spinning the fiber as usual and converting thenonmetallized azo compounds to their metallizedform if desired. Also themetallizing agent can be incorporated in the spinning dope, the fiberspun as usual and then dyed with the non-metallized monoazo compounds toform the metal complex on the fiber. The new metallized dyes of ourinvention are preferably formed by heating the nonmetallized azo dyewith the metallizing agent in organic solvents, ,such as, for example,cellulose acetate, cellulose acetate-propionate, acrylonitrile polymers,polyarnides, ethylene glycol monomethyl ether and formamide.

Both the non-metallized and metallized monoazo compounds of ourinvention are dyes for fibers prepared from graft polymers obtained bygraft polymerizing acrylonitrile alone or together with one or moreother monoethylenic monomers with a preformed polymer. The preformedpolymer can be a homopolymer (a polymer prepared by polymerization of asingle monomer) or it can be an interpolymer such as a copolymer (apolymer prepared by the simultaneous polymerization in a single reactionmixture of two monomers) or a terpolymer (a polymer prepared by thesimultaneous polymerization in a single reaction mixture of threemonomers), or the like, and the graft polymers for which the dyes areparticularly useful are those containing atleast 5% by weight ofcombined acrylonitrile grafted to the preformed polymer molecule. V

The graft polymers which can be dyed using the nonmetallized andmetallized dyes are thus polymers having directed placement of thepolymerized monomeric units in the graft polymer molecule asdistinguished from the t random distribution obtained in interpolymerswhich are prepared by simultaneous polymerization of all of themonomeric materials in the polymer. The preformed polymer can be eitherahomopolymer of any of the wellknown polymerizable monomers containing asingle CH=C group and desirably a CH =C group, or an interpolymer of twoor more of such monomers; and the grafting can be effected with thepreformed homopolymer or interpolymer in the polymerization mixture inwhich it was formed (i. e. a live polymer) or with the.preformedpoly-merisolated from the polymerization mixture in which itwas formed (i. e. a dead polymer).

The preformed polymer desirably is a homopolymer of a vinyl pyridine, anacrylamide, a maleamide, a fumaramide, an acrylate, a methacrylamide, amethacrylate, an itaconamide, a citraconamide, a fumaramate, anitaconamate, a .citraconamate, a maleamate, or a vinyl ester; or aninterpolymer of two or more of such monomers with each other or of atleast one of such monomers with one or more different monoethylenicmonomers characterized by a CH=C group such as styrene, acrylonitrile,substituted styrenes, vinyl or vinylidene chlorides, vinyl ethers,dialkyl maleates, alkenyl ketones, dialkyl fumarates, acrylic acid,methacrylic acid, substituted acrylonitriles, fumaronitrile, ethyleneand the like.

The graft polymerization is-efiected by polymerizing acrylonitrile or amixture of acrylonitrile with any other monoethyl'enic monomer,including any of the monomers enumerated hereinabove, with the preformedlive or dead homopolymer or interpolymer' whereby the acrylonitrilealone or together with another grafting monomer is combined with thepreformed polymer molecule to give a graft polymercontaining from '5 to95% by weight of combined acrylonitrile.

The new azo compounds of our invention are of parcular utility fordyeing fibers prepared from a graft polymer obtained by graftpolymerizing acrylonitrile and an acrylamide or methacrylamide with apreformed copolymer of acrylonitrile and the ide or methacrylamide.

U. S. Patent 2,620,324, issued December 2, 1952; U. S. Patent 2,649,434,issued August 18, 1953, and U. S. Patent 2,657,191, issued October 27,1953, disclose other typical graft polymers that can be dyed with thenew azo compounds of our invention.

The following examples in which parts are expressed as parts by weightillustrate our invention.

same or different acrylam- EXAMPLE 1 10.8 grams of sodium nitrite weredissolved in 78 cc. of concentrated sulfuric acid (94% The resultingsolution was then cooled to C. and 155 grams of propionic-acetic 1:5)acids were added at a temperature below C. To the well stirred solutionthere were added 23.2 grams of Z-aminobenzothiazole while maintainingthe temperature of the reaction mixture at 3 C. to 5 C. 155 grams ofpropionic-acetic (1:5) acids were then added at a temperature of 3 C. to5 C. and this temperature was maintained for an additional two hours.The reaction mixture thus obtained was then added, with stirring, below5 C. to a suspension of 32.7 grams of secondary butyl citrazinate in 230cc. of propionic-acetic (1:5) acids. The cooling bath was removed andthe mineral acid present was made neutral to Congo red paper withammonium acetate. During the neutralization the temperature rose toabout 28 C. The reaction mixture Was then allowed to stand for 2 hoursafter which it was drowned in 3 liters of water. The reaction productwhich precipitated was recovered by filtration,

washed well with cold water and dried. 34 grams of the dye compoundhaving the formula:

CH3 S COOHCHnCHs were obtained as an orange colored product. This dyecompound dyes cellulose acetate bright orange sha'des having goodlight-fastness and dyes the acrylonitrile graft polymer specificallydescribed hereinafter shades having good fastness to light.

EXAMPLE 2 of propionic-acetic (1:5) acids. The mineraliacid prestionmixture was 'The dye product formic acid, 4 cc.

cut was made neutral to'Congo red paper by the addition of ammoniumacetate and the reaction mixture was allowed to stand at roomtemperature for 2 hours and then poured into 2000 parts of tap water.The reaction product which precipitated was recovered by filtration,washed with cold water until neutral and dried at 60 C. 18 parts' of adye compound which dyes cellulose acetate and nylon, for example, orangeshades were obtained.

EXAMPLE 3 parts of concentrated sulfuric acid were added at roomtemperature to a slurry of 11.4 parts of Z-amino-6-methylsulfonylbenzothiazole in 120 parts of water. The temperature ofthe reaction mixture rose to about 90 C. and the2-amino-6-methylsulfonylbenzothiazole dissolved. After cooling to -10C., a solution of 4.2 parts of sodium nitrite in 47 parts ofconcentrated sulfuric acid was carefully added to the reaction mixturewith stirring while keeping the temperature of the reaction mixture at 5C. or below. After stirring for 2 hours at -5 C., the diazonium solutionresulting was added to a solution of 11.8 parts of cyclohexylcitrazinate in parts of propionic-acetic (1:5) acids at 5 C. The mineralacid present in the reaction mixture was made neutral to Congo red paperby the addition of sodium or. ammonium acetate following which thereaction mixture was poured into 2000 parts of cold water. The dyeproduct which precipitated was recovered by filtration, washed well withcold water and dried at 60 C. 21.1 parts of a dye compound which dyesthe acrylonitrile graft polymer specifically described hereinaftershades having good fastness to light were obtained as an orange solid.

EXAMPLE 4 with stirring while keeping the temperature of the reactionmixture at 5 C. or below. After stirring for 2 hours at --5 C., thediazonium solution resulting was added to a solution of 10.6 grams ofsecondary butyl citrazinate in 150 parts of propionic-acetic 1:5 acidsthe mineral acid present in the reaction mixture was made neutral toCongo red paper by the addition of sodium or ammonium acetate followingwhich the reacwhich precipitated was filtration, washed well with coldwater and dried at 60 C. 19.2 parts of a dye compound which dyescellulose acetate yellow] shades having good light fastness andtheacrylonitrile graft polymer specifically described hereinafter shadeshaving good light fastness were obtained.

recovered by EXAMPLE 5 By the use of 9.2 parts of ethyl citrazinate inExample 4 in place of secondary butyl citrazinate 16.8 parts of a dyecompound which dyes the acrylonitrile graft polymer specificallydescribed hereinafter shades having good fastness to light wereobtained.

EXAMPLE 6 3.6 grams of 2-amino-6-methoxybenzothiazole were dissolved ina mixture consisting of 6 cc. of 80% aqueous poured into 2000 parts ofcold water.

of glacial acetic acid and 8 cc. of l concentrated.-HCl. The resultingsolution was cooledto 5: .C. and a solution of 1.42 grams of sodiumnitritein 3 cc. of water. -.was added. at. a, temperaturebelow 5 C;following which the reaction mixture was stirred for 2' hours longerwhile maintaining the temperature below C. The diazonium solution thusobtained was run into a mixture of 3.66 grams of ethyl citrazinate, 8-grams ofanhydrous sodium. acetate and 60 cc. of 60% aqueous formic acid.The coupling. reaction which takes place was allowed to proceed for 2hours at room temperature following which the reaction mixture waspoured into! 800 cc. of water. The dye compound which precipitated was.recovered by filtration, washed well with water and dried. 6.1 grams ofa dye compound which dyes the acrylonitrile graft polymer specificallydescribed hereinafter shades of good light fastness were obtained as. anorange solid. When applied, to a cellulose acetate fabric and metallizedthereon, brilliant red-violet dyeings having excellent resistance to theaction of light and laundering are obtained. The dye compound of' thisexample is the same as the dye-compoundof Example 2.

EXAMPLE 7 130 parts of concentrated sulfuric acid were added at roomtemperature to a slurry of 11.4 parts of 2-amino-6-methyl-sulfonylbenzothiazole in 120 parts of water. The temperature ofthe reaction mixture rose to about 90 C. and the2-amino-6-methyl-sulfonylbenzothiazole dissolved. After cooling to -10C., a solution of 4.2 parts of sodium nitrite in 47 parts ofconcentrated sulfuric acid was carefully added to the reaction mixturewith stirring while keeping the temperature of the reaction mixture at 5C. or below. After stirring for 2 hours at 5 C., the diazonium solutionresulting was added to a solution of 13.4 parts ofn-butyl-2-hydroxy-6-n-butoxyisonicotinate in 125 parts ofpropionic-acetic (1:5) acids .at 5 C. The mineral acid present in thereaction mixture was made neutral to Congo red paper by the addition ofsodium or ammonium acetate following which the reaction mixture waspouredinto 2000 parts of water. The dye product which precipitated wasrecovered by filtration, washed well with water and dried at 60 C. 18.5parts of a dye compound which dyes cellulose acetate yellow shades wereobtained.

EXAMPLE 8 50 parts of propionic-acetic (1:5) acids were added at 10 C.to a solution of 3.8 parts of sodium nitrite in 45 parts of concentratedsulfuric acid (94%). 8.9 parts of 4,6-dimethyl,-2-aminobenzo-thiazolewere added below 5 C. to the sodium nitrite solution and the resultingreaction mixture was stirred for 2 hours at 0 C.5 C. The diazoniumsolution thus obtained was run into 11.8 parts of cyclohexyl citrazinatein 140 parts of propionic-acetic (1:5) acidsand the resulting solutionwas stirred for 1 hour at a temperature below 10 C. following which itwas poured into 2000 parts of water and the reaction product whichprecipitated was recovered by filtration, washed with water and dried at60 C. under vacuum. 16 parts of a dye compound which dyes celluloseacetate orange shades were obtained.

EXAMPLE 9' By the use of 4.22 grams of the isobutyl ester of citrazinicacid in Example 6 in place of ethyl citrazinate an orange colored dyecompound which dyes the acrylonitrile graft polymer specificallydescribed hereinafter shades having good fastness to light was obtained.When applied to a cellulose acetate fabric and metallized thereon,brilliant red-violet dyeings having excellent resistance to the actionof light and laundering are obtained.

8? EXAMPLE 10 By the use of an equivalent amount of 2-amino-6-methyl-benzothiazole in Example 1 in place of Z-aminobenzothiazole anorange dye compound was obtained. It dyes cellulose acetate brightorange shades having good light, fastness and dyes the acrylonitrilegraft polymer specifically described hereinafter shades having goodfastness to light.

EXAMPLE 11 1 gram of the dye compound of Example 1 was refluxed in 16cc. of acetone and 2.2 cc. of 28% aqueous ammonium hydroxide were addedfollowed by the addition of 0.74 gram of Ni(OOCCI- I -4H O in 16 cc. ofacetone. The resulting solution was refluxed with stirring for 2.5 hoursand then poured into 450 cc. of water. The metallized dye product whichprecipitated was recovered by filtration, washed well with water anddried. 1.15 grams of a red pigment were thus obtained. When this pigmentis intimately dispersed (as by grinding) in finely divided condition ina cellulose acetate-acetone dope which is then cast into film orextruded in filaments, brilliant red products having excellent fastnessto light and washing are obtained.

EXAMPLE 12 1.01 grams of the dye compound of Example 2 were refluxed in16 cc. of acetone and 2.2 cc. of 28% aqueous ammonium hydroxide wereadded followed by the addition of 0.74 gram of Ni(OOCCH -4H O in 16 cc.of acetone. The resulting solution was refluxed with stirring for 2.5hour-s and then poured into 450 cc. of water. The metallized dye productwhich precipitated was recovered by filtration, washed well with waterand dried. 1.16 grams of a reddish-violet pigment were thus obtained.When this pigment is intimately dispersed (as by grinding) in finelydivided condition in a cellulose acetate-acetone dope which is then castinto film or extruded in filaments, reddish-violet products havingexcellent fastness to light and washing are obtained.

EXAMPLE 13 1.25 grams of the dye compound of Example 3 were refluxed in16 cc. of acetone and 2.2 cc. of 28% aqueous ammonium hydroxide wereadded followed by the addition of 0.74 gram of Ni(OOCCI-I -4H O in 16cc. of acetone. The resulting solution was refluxed with stirring for2.5 hours and then poured into 450 cc. of water. The metallized dyeproduct which precipitated was recovered by filtration, washed well withwater and dried. 1.40 grams of a red pigment were thus obtained. Whenthis pigment is intimately dispersed (as by grinding) in finely dividedcondition in a cellulose acetate-acetone dope which is then cast intofilm or extruded in filaments, red products having excellent fastness tolight and washing are obtained.

EXAMPLE 14 1.21 grams of the dye compound of Example 4 were refluxed in16 cc. of acetone and 2.2 cc. of 28% aqueous ammonium hydroxide wereadded followed by the addition of 0.74 gram of Ni(OOCCH -4H O in 16 cc.of acetone. The resulting solution was refluxed with stirring for 2.5hours and then poured into 450 cc. of water. The metallized dye productwhich precipitated was recovered by filtration, washed well with waterand dried. 1.36 grams of a red pigment were thus obtained. When thispigment is intimately dispersed (as by grinding) in finely dividedcondition in a cellulose acetate-acetone dope which is then cast intofilm or extruded in filaments, red products having excellent fastness tolight and Washing are obtained. i

1.15 grams of the dye compound of Example 5 were A refluxed in 16 cc. ofacetone and 2.2 cc. of 28% aqueous ammonium hydroxide were addedfollowed by the addi tion-of 0.74 grams of Ni(OCCH -4H O in 16 cc. ofacetone. The resulting solution was refluxed with stirring for 2.5 hoursand then poured into 450 cc. of water. The metallized dye product whichprecipitated was recovered by filtration, washed well with water anddried. 1.30 grams of a red pigment were thus obtained. When this pigmentis intimately dispersed (as by grinding) in finely divided condition ina cellulose acetate-acetone dope which is then cast into film orextruded in filaments, red products having excellent fastness to lightand washing are obtained.

EXAMPLE 16 A cellulose acetate fabric dyed with a 3% dyeing of the dyeproduct of Example 7 was padded with a 2% aqueous solution of nickelthiocyanate under conditions such that a 60 to 100% pick up, based onthe weight of the goods, was obtained. The cellulose acetate fabric wasair dried and then aged in a steam chest under p. s. i. pressure for 10to minutes after which it was scoured at 60 C. with soap and water,rinsed well with water and dried. The cellulose acetate fabric was dyeda bright red shade in contrast to its original yellow color. Themetallized dyeing thus obtained showed no alteration when subjected to astandard AATCC wash test at 160 F. Further, while the original yellowdyeing showed a break after 5 hours on the Fade-Ometer, the metallizeddyeing showed no fading after hours exposure on the Fade-Ometer.

The above example was repeated replacing the nickel thiocyanate solutionwith a 2% aqueous solution of cobalt thiocyanate. The metallized dyeingthus obtained possessed a similar red shade having excellent fastness towashing and light.

EXAMPLE 17 A cellulose acetate fabric dyed with a 3% dyeing of the dyeproduct of Example 2 was padded with a 2% aqueous solution of nickelthiocyanate in accordance with the procedure described in Example 16.The cellulose acetic fabric was dyed an attractive violet shade havingEXAMPLE 18 A cellulose acetate fabric dyed with a 3% dyeing of the dyeproduct of Example 8 was padded with a 2% aqueous solution of nickelthiocyanate in accordance with the procedure described in Example 16.The cellulose acetate fabric was dyed an attractive red shade which hasexcellent fastness to light. The metallized dyeing bled slightly uponbeing subjected to a standard AATCC wash test at 160 F. with soap andwater. However, no bleeding was observed when the wash test wasconducted at 140 F.

When the above example was repeated using a 2% aqueous solution ofcobalt thiocyanate in place of the nickel thiocyanate solution, anattractive red dyeing which has substantially the same fastness to lightandwashing as the dyeing of the example was obtained.

EXAMPLE 19 I 5 parts of the dye product of Example 7, 60 parts of themonomethyl ether of ethylene glycol, 2 parts of 28% 10 pigment whichprecipitated was recovered by filtration, washed well with hot water andthen dried at 110 C. A yield of 6.5 parts was thus obtained. When thisred pigment is initimately dispersed (as by grinding) in finely dividedcondition in a cellulose acetate-acetone dope which is then cast intofilm or extruded in filaments and woven or knitted into cloth, apleasing red fabric of excellent resistance to the action of light andlaundering is obtained.

EXAMPLE 20 A cellulose acetate fabric dyed with a 3% dyeing of the dyeproduct of.Example 1 was padded with a 2% aqueous solution of nickelthiocyanate in accordance with the procedure described in Example 16.The cellulose acetate fabric was dyed a brilliant bluish-red shade whichhas excellent resistance to the action of light and laundermg.

EXAMPLE 21 The dye of Example 3 was prepared as before except that afterfiltering and washing the dye product was suspended in 500 cc. of waterand brought to 60 C. 100 cc. of a 20% aqueous solution of nickelthiocyanate was added at a temperature of 60 C.- C. with good stirringover a period of about 30 minutes after which the temperature of thereaction mixture was raised to about 90 C. with stirring and whilekeeping the mixture slightly alkaline by the addition of 28% aqueousammonium hydroxide. When the reaction was complete, as evidenced by nomore acid formation, the reaction mixture was filtered to obtain 28parts of metallized dye as a red solid. This metallized dye product,when incorporated into objects cast, molded or extruded from celluloseacetate compositions, yields bright scarlet objects of excellentfastness to light and Washing.

EXAMPLE 22 1.11 grams of the dye compound of Example 9 were refluxed in16 cc. of acetone and 2.2 cc. of 28% aqueous ammonium hydroxide wereadded followed by the addition of 0.74 gram of Ni(OOCCH -4H O in 16 cc.of acetone. The resulting solution was refluxed with stirring for 2.5hours and then'poured into 450 cc. of water. The metallized dye productwhich precipitated was recovered by filtration, washed well with waterand dried. 1.26 grams of a reddish-violet pigment were thus obtained.When' this pigment is intimately dispersed (as by grinding) in finelydivided condition in a cellulose acetateacetone dope which is then castinto film or extruded in filaments, reddish-violet products havingexcellent fastness to light and washing are obtained.

EXAMPLE 23 1.06 grams of the dye compound of Example 10 were refluxed in16 cc. of acetone and 2.2 cc. of 28% aqueous ammonium hydroxide wereadded followed by the addition of 0.74 gram of Ni(OOCCH -4H O in 16 cc.of acetone. The resulting solution was refluxed with stirring for 2.5hours and then poured into 450 cc. of water. The metallized dye productwhich precipitated was recovered by filtration, washed well with waterand dried.

' 1.21 grams of a bluish-red pigment were thus obtained.

When this pigment is "intimately dispersed (as by grinding) in finelydivided condition in a cellulose acetateacetone dope which is then castinto film or extruded in filaments, bluish-red products having excellentfastness to light and washing are obtained.

The following tabulation further illustrates the monoazo compounds ofour invention and sets forth (1) the colors the non-metallized compoundsyield on cellulose acetate and (2) the colors obtained on celluloseacetate when the non-metallized compounds are metallized on the fiber.C. A. refers to cellulose acetate, Original refers to the non-metallizeddyeing and Final refers to the metallized dyeing.

Color on CA 2-Aminobenzothiazo1e C om- Coupling Component Metalliz ing Ypound Aggnt Original Final G-Methoxy Ni(SCN)a orangenu violet. Do doCO(SCN)2 d0 Do. G-Methylsulfonyl n-Butyl 2-hyd10 N KSON )2"...

o fi-Metliylthio Do isonicotinate.

do u-Butyl 2-Hydroxy imamcotinate.

. 0 fl-Megzhoxyethyl citrazinate o sec-gutyl citrazinate o Oyclohexylcitmzinate Cyclohexyl citrazinate Isobutyl citrazinate 13 Preparation ofacrylonitrile graft polymer 3.0 g. of acrylonitrile and 7.0 g. ofN-methyl methacrylamide were emulsified in 40 cc. of water containing0.15 g. of potassium persulfate and 0.01 g. of tertiary dodecylmercaptan. The emulsion was heated at 60 C. until 94% or more of themonomers had copolymerized. This result is usually accomplished byheating for about 12 hours. The copolymer contained approximately 30% byweight of acrylonitrile and 70% by weight of N-methyl methacrylamide.The mixture was then cooled to room temperature, 50 cc. of Water addedand the mixture agitated until a homogeneous solution of dope containing10% by weight of the copolymer resulted.

30.7 g. (3.07 g. of copolymer) of the above prepared solution or dope ofthe copolymer were placed in a jacketed reactor provided with anagitator and heat exchanger. There were then added 10 g. ofacrylonitrile, 114 cc. of water, 0.58 g. of 85% phosphoric acid, 0.1 g.of potassium persulfate, 0.17 g. of potassium metabisulfite, 0.1 g. oftertiary dodecyl mercaptan and 0.56 g. of a 30% solution in water ofN-methyl methacrylamide and the mixture heated, with stirring, to 35 C.and then allowed to level oii at 3739 C. After the heat ofpolymerization had been removed and when the conversion of theacrylonitrile to polymer had reached 96% or more, which is usuallyaccomplished in a period of about 12 hours, the temperature was raisedto 90 C. The mother liquor was removed by centrifuging thepolymerization mixture, the polymer precipitate being reslurried twicewith water and centrifuged to a 70% moisture cake. The cake was driedunder vacuum at 80 C. in an agitated dryer. The overall yield ofmodified polyacrylonitrile product was over 90%. After hammermilling,the dry powder, now ready for spinning, was stored in a moisture proofcontainer.

The acrylonitrile graft polymer prepared as above and containing about18% by weight of N-methyl methacrylamide was soluble inN,N-dimethylformamide. Fibers spun by extruding a solution of thepolymer prod uct in N,N-dimethylformamide into a precipitating bath hada softening temperature of about 240 C., an extensibility of about 2030percent depending on the drafting an relaxing conditions, and showedexcellent aflinity for dyes.

In order that the preparation of the azo compounds of our invention maybe entirely clear, the preparation .of certain intermediates used intheir manufacture is described hereinafter.

Preparation of 2-amino-6-methylsnlfonylbenzothiazole A solution of 200parts of bromine in 300 parts of acetic acid was added over the courseof about 1 hour to a mixture of 171 parts of p-aminophenylmethylsulfoneand 202 parts of sodium thiocyanate in 1750 parts of acetic acid. Thetemperature was held below 35 C. during the addition and after completeaddition of the bromine-acetic acid mixture, the reaction mixture wasstirred for 18 hours. The reaction product was recovered on the filterby filtration, washed with acetic acid and then dispersed in 6000 partsof water. The reaction mixture thus obtained Was heated to boiling andthen an alkali such as caustic soda or sodium carbonate was added untilthe pH of the reaction mixture was about 6. The reaction mixture wasthen cooled, filtered and the reaction product which collected on thefilterwas washed well with water and dried at 120 C. 145 to 160 parts of2-amino-6-methylsulfonylbenzothiazole were obtained as light yellowcrystals melting at 226 228 C.

Preparation of Z-acetylamin-6-thiocyanobenzothiazole To a soltuion of18.6 parts of aniline and 30.4 parts of ammonium thiocyanate in 300parts of acetic acid at 15 C. 14.2 parts of chlorine were bubbled in at15 C.-17 C. 30 minutes after addition of the chlorine 15.6 parts ofsodium acetate and 30.4 parts of ammonium thiocyanate were added to thereaction mixture. Whileacid and then suspended in 600 parts of water.The mixture thus obtained was heated to boiling and filtered. 30 partsof sodium acetate were added to the filtrate and the solid whichprecipitated was collected at C. on a filter, washed with 200 parts ofcold water and dried at 100 C. 30 parts of a product melting at 187C.-188 C. were thus obtained.

30 parts of acetic anhydride were added at C. to a solution of 52.6parts of the above product in 81 parts of acetic acid, and thetemperature of the reaction mixture was held at 80 C. C. for one hour.The reaction mixture was then poured into 1000 parts of cold water andthe product which precipitated was recovered by filtration, washed with500 parts of water and-then dried at 60 C. 62 parts of2-acetylamino-6-thiocyanobenzothiazole melting at 247 C.-249 C. werethus obtained.

Preparation of Z-amino-6-ethylsulfonylbenzothiazole 10 minutes and aftercooling the reaction mixture tov 20 C., 16.3 parts of ethyl iodide wereadded at one time and the reaction mixture resulting was refluxed forone hour. The reaction mixture was then poured into 1000 parts of waterand the product which precipitated was recovered by filtration, washedwell with water and dried at 60 C. 23.6 parts of2-acetylamino-6-ethylthiobenzothiazole melting at 168 C.169 C. were,obtained. If desired, the quality of the product can be checked byhydrolyzing a little of the product with acid to 2-amino-6-ethylthiobenzothiazole melting at 137 C.139 C.

19 parts of 30% aqueous hydrogen peroxide were added to a solution of15.5 parts of 2-acetylamino-6- ethylthiobenzothiazole in 53 parts ofacetic acid while maintaining the temperature of the reaction mixturebetween 80 C.-90 C. The reaction mixture was maintained at thistemperature for one hour and then poured into 500 parts of cold Water.The solid present in the reaction mixture was recovered by filtrationand then suspended in a mixture of 800 parts of water and parts ofconcentrated hydrochloric acid. The reaction mixture thus obtained washeated to boiling and then filtered. The filtrate was neutralized withsodium acetate, cooled to 25 C. and filtered. The product collected onthe filter was washed with cold water and dried at 60 C. 8.5 parts of2-amino-6-ethylsulfonylbenzothiazole melting at 173 C.-175 C. were thusobtained.

Preparation of 2-amin0-6-is0propylsalfonylbenzothiazole prepared by theuse of 17.76 parts of n-propyl iodide in place of isopropyl iodide inthe foregoing example.

. Preparation of 2-amin0-6-isobatylsalfonylbenzothiazole bromide inplace of ethyl iodide. The melting point of theZ-acetylamino-6-isobutylthiobenzothiazole obtained 1 was 167 C.-168 C.while that of the final product Z-amino-6-isobutylsulfonylbenzothiazolewas 206 C.- 207 C.

2-amino-6-n-butylsulfonylbenzothiazole is similarly prepared by using14.3 parts of n-butyl bromide in place of isobutyl bromide in theforegoing example.

Preparation of 2-amino-6-triflu0romethylsulfonylbenzothiazole 75 partsof bromine in 120 parts of acetic acid were added gradually withstirring to a solution of 98 parts ofp-aminophenyltrifiuoromethylsulfone and 76 parts of sodium thiocyanatein 700 parts of acetic acid. The additionof the bromine was-begun atroom temperature and the temperature of the reaction mixture Was keptbelow 35C. during the addition. The temperature ordinarily rises toabout 32 C. The reaction mixture resulting was stirred for'24 hoursat-ro0m temperature following which it was poured into 5000 parts ofcold water and the mineral acid therein neutralized by the addition ofsodium acetate with good stirring. The product which formed wasrecovered by filtration, washed well With cold water and dried at 110 C.33 to 70 parts of 2-amino-6-trifluoromethylsulfonylbenzothiazole meltingat 206-208 C. were thus obtained.

Preparation of 2-amino-dvtrifluoromethylbenzothiazole 12.5 parts ofbromine in 20 parts of acetic acid were added dropwise, with stirring,to a solution of 12.4 parts ofp-aminobenzotrifiuoride and 12.7parts ofsodium thiocyanate in 115 parts of acetic acid While maintaining thetemperature of the reaction mixture below 35 C. The reaction mixtureresulting was stirred for 12 hours following which the' solid presentvtherein was removed by filtration. The filtrate was poured into 1000parts of water and the mineral acid therein was neutralized by theaddition of sodium acetate with good agitation. The product whichformedwas recovered by filtration,,washed well with. cold Water and, driedunder vacuum at 45 C. 717 -102 parts of2-amino-6-trifiuoromethylbenzothiazole melting at 115.5-116.5 C. werethus obtained.

Preparation of 2-amino-6-,B-hya'roxyethylbenzothiazole 255.7 grams ofbromine in 400 cc. of acetic acid were added gradually over a period of1 hour with good stirring to a solution of 219.2 grams ofp-aminophenylethyl alcohol and 259.2 grams of sodium thiocyanate in 2400cc. of acetic acid while maintaining the temperature of the reactionmixture below 15 C. The reaction mixture resulting was stirred for 2hours at C.-12 C. and the product which formed was recovered on thefilter by filtration and washed with 300 cc. of acetic acid. The productfilter cake thus obtained was dissolved in 1600 cc. of water at about 40C. and the reaction mixture was made alkaline by the addition of sodiumhydroxide. The reaction mixture thus obtained was heated to boiling andthen cooledto C. and filtered. The product obtained onthe filter waswashed with Water until neutral and then dried at 100 C. 206 to 230grams of 2-amino-6- 3-hydroxyethylbenzothiazole were thus obtained inthe form of white crystals melting at 175 C.177 C.

Preparation of secondary butyl citrazinate 50 grams of citrazinic acid,15 grams of sulfonic acid (94% and 200 cc. of secondary butyl alcoholwere refluxed together for 6 hours using a water trap in the condenserto remove the water formed. The reaction mixture-was then cooled, 100cc. of water were added and the crystals of secondary butyl citrazinatewhich precipitated' were recovered by filtration and washed withcoldethyl alcohol. 38 grams of product melting at 212 C.2l3 C. were thusobtained. Upon recrystallization from hot ethyl alcohol the secondarybutyl citrazinate product melted at 217 C.218 C.

Preparation of isobutyl citrazinate 200 grams of citrazinic acid and 500cc. of isobutyl alcohol were stirred in a suitable reaction vessel anddry HCl was passed through the reaction mixture until the temperaturerose to reflux. The reaction mixture was refluxed overnight followingwhich Water was added until a solid formed. The solid formed wasrecovered by filtration and dissolved in an aqueous sodium hydroxidesolution. Acetic acid was added until a pH of 6 was reached.2-isobutoxy-6-hydroxyisonicotinic acid isobutyl ester precipitated as asolid and was recovered by filtration and dried. A yield of 48 gramsmelting at 110 C.- 1105 C. was obtained. 50 cc. of acetic acid wereadded to the filtrate obtained from the ester recovery o eration.isobutyl citrazinate precipitated and was recovered by filtration anddried. 110 grams of product melting at 191 C.192 C. were thus obtained.

Preparation of cyclohexyl citrazinate 50 grams of citrazinic acid, 200cc. of cyclohexanol and 15 cc. of concentrated sulfuric acid (94%) wererefluxed together for 6 hours, using a water trap in the condenser toremove the Water as formed. The reaction mixture was then cooled, pouredin 500 cc. of water and filtered. The solid recovered on the filter waswashed with cold ethyl alcohol and recrystallized from hot ethylalcohol. 30 to 40 grams of cyclohexyl citrazinate were recovered in theform of white crystals melting at 217 C.-218 C.

Preparation of isopropyl citrazinate 50 grams of citrazinic acid, 200cc. of isopropyl alcohol and 15' cc. of concentrated sulfuric acid (94%)were refluxed together for 6 hours using a water trap in the condenserto remove the water as formed. The reaction mixture was cooled, pouredinto 500 cc. of water and filtered. The solid recovered on the filterwas washed with cold ethyl alcohol and then recrystallized from hotethyl alcohol. 25 to 35 grams of isopropyl citrazinate were thusobtained as crystals melting at 232 C.233 C.

Preparation of ,B-methoxyethyl citrazinate 50 grams of citrazinic acidwere suspended in 200 cc. of the monomethyl ether of ethylene glycol.Dry HCl was passed through the reaction mixture at a temperature ofabout 70 C. and the citrazinic acid went into solution. Admission of dryHCl was continued at C. C. for 3 hours longer. Then an equal volume ofwater was added and the reaction mixture was cooled to 10 C. Thecrystals of B-methoxyethyl citrazinate which precipitated were recoveredby filtration and recrystallized from the monomethyl ether of ethyleneglycol. Since the product contains some high melting material, it wasdissolved in an aqueous sodium carbonate solution and brought to a pH of4.5 with acetic acid. The purified product precipitated and wasrecovered by filtration and dried. 31 grams of product melting at 183 C.were thus obtained.

By the use of the monomethyl ether of ethylene glycol and themono-n-butyl ether of ethylene glycol in the above example in place ofthe monomethyl ether of ethylene glycol, fi-ethoxyethyl citrazinate and[3-n-butoxyethyl citrazinate, respectively, are obtained.

Another alkali metal thiocyanate such as potassium thiocyanate, forexample, can be used in place of sodium thiocyanate in the foregoingexamples dealing with the preparation of Z-aminobenzothiazole compounds.Similarly, another alkaline agent, such as sodium carbonate, sodiumbicarbonate, potassium carbonate, potassium bicarbonate, ammoniumacetate or potassium acetate, for example, can be used to neutralize themineral acid in place of sodium acetate.

The preparation of p-aminophenyltrifluoromethylsulfone is described inBritish Patent 485,592.

The non-metallized monoazo dye compounds of our invention can be appliedto cellulose alkyl carboxylic acid esters having 2 to 4 carbon atoms inthe acid groups thereof, nylon, an acrylonitrile polymer, such aspolyacrylonitrile and acrylonitrile graft polymers, and polyester, suchas polyethylene terephthalate, textile materials and the metallized azodye compounds of our invention can be applied to nitrogenous textilematerials such as, for example, wool, silk, nylon and acrylonitrilepolymers, such as polyacrylonitrile and acrylonitn'le graft polymers, inthe form of an aqueous dispersion and are ordinarily so applied.

To illustrate, the dye compound is finely ground with a dispersing agentsuch as sodium lignin sulfonate, Turkey red oil, soap, or an oleylglyceryl sulfate and the resulting mixture is dispersed in wate The dyebath thus prepared is heated to a temperature approximately 45 C.-

' 55 C. and the textile material to be dyed is immersed in the dyebath,following which the temperature is gradually raised to 80 C.-90 C. andmaintained at this temperature until dyeing is complete, usuallyone-half to two hours. From time to time throughout the dyeingoperation, the material is worked to promote even dyeing. Uponcompletion of the dyeing operation, the textile material is removed fromthe dye bath, washed with an aqueous soap solution, rinsed well withwater and dried. In the case of certain of the acrylonitrile graftpolymers described hereinbefore it is necessary to dye at the boil foran extended period of time. Instances may be encountered where the fiberis not satisfactorily colored by the dyeing procedure just described. Inthese instances special dyeing techniques, such as the use of pressure,for example, developed by the art for the coloration of materialsdiflicult to color may be employed.

Widely varying amounts of dye can be used in the dyeing operation. .Theamount of dye used can be, for example, /3 to 3% (by weight) of that ofthe textile material although lesser or greater amounts of the dye canbe employed.

The following example illustrates one satisfactory way in which thefibers of the acrylonitrile graft polymers can be dyed using either thenon-metallized or metallized azo compounds of our invention. 16milligrams of dye are ground with an aqueous solution of sodium ligninsulfonate until well dispersed or alternately the dye can be dissolvedin 5 cc. of hot Cellosolve. The dispersion or solution, as the case maybe, is then poured into 150 cc. of water to which a small amount of asurface-active agent such as Igepon T Nekal BX (sodiumalkylnaphthalenesulfonate)v or Orvus (sodium lauryl sulfate-type) hasbeen added. The dye bath is then brought to the desired temperature and5 grams of Well wet-out fibers of the graft polymer are added thereto.Dyeing is continued until the proper shade is reached. From time to timethroughout the dyeing operation, the material is Worked to promote evendyeing.

The expression propionic-acetic (1:5) acids refers to a mixture ofpropionic and acetic acids in which there are five parts by volume ofacetic acid to 1 part of volume of propionic acid.

The non-metallized azo compounds dye nylon substantially the same shadeas they dye acrylonitrile polymers.

Acrylonitiile graft polymers including those of the type specificallydescribed hereinbefore are described and claimed in Coover U. S.application Serial No. 408,012, filed February 3, 1954.2-amino-6-trifluoromethylsulfonylbenzothiazole is described and claimedby Straley and Fisher U. S. application Serial No. 413,954 filed March3, 1954, now abandoned. 2-amino-6-trifluoromethylben zothiazole isdescribed and claimed by Straley and Fisher, U. S. application SerialNo. 413,955, filed March 3, 1954, now abandoned.

We claim:

1. The monoazo compounds selected from the group consisting of themonoazo compounds and their metal complexes containing a metal selectedfrom the group consisting of chromium, cobalt, copper, iron, manganese,nickel and vanadium, said monoazo compounds having the formula:

Ar\ ci OX N \N wherein Ar represents an ortho-arylene radical of thebenzene series devoid of a sulfonic acid group, R represents a memberselected from the group consisting of a hydrogen atom, an alkyl grouphaving 1 to 4 carbon atoms, an alkoxyalkyl group having 3 to 6 carbonatoms and a cyclohexyl group and X represents a member selected from thegroup consisting of a hydrogen atom and an alkyl group having 1 to 4carbon atoms.

2. A complex metal compound which contains one of the metals selectedfrom the group consisting of chromium, cobalt, copper, iron, manganese,nickel and vanadium in complex combination with a monoazo compoundhaving the formula:

COOR

Ar \GN=N HO oxwherein Ar represents an ortho-arylene radical of thebenzene series devoid of a sulfonic acid group, R represents a memberselected from the group consisting of a hydrogen atom, an alkyl grouphaving 1 .to 4 carbon atoms, an alkoxyalkyl group having 3to 6 carbonatoms and a cyclohexyl group and X represents a member selected from thegroup consisting of a hydrogen atom and an alkyl group having 1 to 4carbon atoms.

3. A complex metal compound which contains one of the metals selectedfrom the group consisting of chromium, cobalt, copper, iron, manganese,nickel and vanadium in complex combination with a monoazo compoundhaving the formula:

wherein Ar represents an ortho-arylene radical of the benzene seriesdevoid of a sulfonic acid group and R represents an alkyl group having 1to 4 carbon atoms.

4. Complex nickel compounds of the monoazo compounds having the formulaset forth in claim 2.

5. Complex nickel compounds of the monoazo compounds having the formulaset forth in claim 3.

6. The monoazo compounds having the formula:

wherein Ar represents an ortho-arylene radical of the benzene seriesdevoid of a sulfonic acid group, R represents a member selected from thegroup consisting of a hydrogen atom, an alkyl group having 1 to 4 carbonatoms, an alkoxyalkyl group having 3 to 6 carbon atoms and a cyclohexylgroup and X represents a member selected from the group consisting of ahydrogen atom and an alkyl group having 1 to 4 carbon atoms.

7. The monoazo compounds having the formula:

COOR

wherein Ar represents an ortho-arylene radical of the benzene seriesdevoid of a sulfonic acid group and R represents an alkyl group having 1to 4 carbon atoms.

8. A complex nickel compound of the azo compound having the formula:

5 O O CHCHzCHs 9. A complex nickel compound of the azo compound havingthe formula:

S COOCHzCI-Ia HO OH N 10. A complex nickel compound of the azo compoundhaving the formula:

HO OH N 11. A complex nickel compound of the azo compound having theformula:

r S C O O CHCHaCHa CHaO:S

,CN=N

HO OH 12. A complex nickel compound of the azo compound having theformula:

s COOCHgOHi CHaOaS- HO OH 13. The azo compound having the formula:

CH3 s\ ooohflomom CN=N HO OH N 14. The azo compound having the formula:

N HO OH 15. The azo compound having the formula:

S COO-eye] hcxyl HO OH N 25 16. The azo compound having the formula:

References Cited in the file of this patent UNITED STATES PATENTS2,068,353 Schneiderwirth Jan. 19, 1937 2,149,051 Helberger et a1. Feb.28, 1939 2,441,612 Argyle et a1. May 18, 1948 2,560,502 Bestehorn et al.July 10, 1951 2,594,803 Riat et al Apr. 29, 1952 2,662,806 Menzi et alDec. 15, 1953 OTHER REFERENCES 7 Kalman: American Dyestuff Reporter,vol. 30, No. 20,

September 29, 1941, pp. 499-503 and 524.

UNITED STATES PATENT OFFICE Certificate of Correction Patent No.2,857,372 October 21, 1958 James M. Straley et al. It is herebycertified that error appears in the printed specification of the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below.

Column 1, Formula 1, for the upper right-hand portion of the formulareading COOA read COOR--; column 9, line 45, Example 17, for acetic readacetate; column 13, line 14, for an read -and-; column 18, lines 47 to52, claim 3, and column 19, lines 2 to 7, claim 7, the formula, eachoccurrence, should appear as shown below instead of as in the patent:

CODE 5 l column 19, claim 9, for the upper left-hand portion of theformula reading GH O- read CH O- Signed and sealed this 7th day of April1959.

Attest:

KARL H. AXLINE, ROBERT C. WATSON, Attracting Ofiicer, Commissioner ofPatents,

1. THE MONOAZO COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF THEMONOAZO COMPOUNDS AND THEIR METAL COMPLEXES CONTAINING A METAL SELECTEDFROM THE GROUP CONSISTING OF CHROMIUM, COBALT, COPPER, IRON MANGANESE,NICKEL AND VANADIUM SAID MONOAZO COMPOUNDS HAVING THE FORMULA: